1. Field of the Invention
The present invention relates to a method of producing a sintered silicon carbide and a sintered silicon carbide produced by the above-mentioned production method. More specifically, the present invention relates to a method of producing a sintered silicon carbide useful as parts for semiconductor production apparatuses, parts for electronic information equipments, parts for structures of vacuum apparatuses and the like, and having high density and high purity, and a sintered silicon carbide obtained by the above-mentioned method.
2. Description of the Related Art
Conventionally, a reaction sintering method is known as one of methods for producing a sintered silicon carbide. This reaction sintering method is composed mainly of (1) a process of dissolving and dispersing a silicon carbide powder, and a carbon powder or an organic substance composed of a carbon source, for example, carbon black, to produce a mixed powder slurry; (2) a process of flowing the resulted mixed powder into a casting mold, extrusion mold or press mold and drying this, to obtain a green body; and (3) a process of heating the green body in one of a vacuum atmosphere or inert gas atmosphere, immersing this into a fused metal silicon, and reacting free carbon in the green body with the silicon sucked into the green body by a capillary phenomenon, to obtain a sintered silicon carbide.
The sintered silicon carbide obtained by the above-mentioned production method have been conventionally used in many applications utilizing excellent properties such as high temperature strength, heat resistance, friction resistance, chemical resistance and the like.
Recently, in the fields of electronic information equipment materials and semiconductor producing materials, increase in the treatment temperature of a wafer, increase in the diameter of a wafer and increase in treatment unit have lead to a requirement of a sintered silicon carbide not manifesting thermal deformation and degeneration by washing with chemical liquid such as hydrofluoric acid and the like, having excellent heat resistance, and having high density and purity.
On the other hand, since a sintered silicon carbide obtained by the above-mentioned reaction sintering method has high strength and is limited in molding working, molding working is often conducted in a stage of production of the above-mentioned green body. In this case, because of the insufficient strength of the green body, and the like, a close attention has been required for production of a sintered silicon carbide, particularly, a sintered silicon carbide of complicated shape. Therefore, further increase in the strength of the green body has been required for improving the molding workability of a sintered silicon carbide.